The human population unbound

Over the past 100 years, global demographic changes have been more than just historic — they have been so sweeping and profound as to rank almost on the scale of an evolutionary leap. What we have witnessed is nothing less than a departure from the demographic rhythms that previously characterized human existence. Across the world we have seen humanity unshackled from practically all the patterns and limits that bound us before, save for reproduction and death itself.

Humans since 1914 have undergone a global population explosion, a health explosion, a fertility revolution, and an urbanization revolution — with further, equally monumental changes currently in the works, promising to transform the world’s population profile in likewise previously unimaginable respects over the century to come.

By very approximate orders of magnitude, it is believed that around 100 billion people have ever been born, with around 90 billion of these souls born before 1914. For that first 90 billion, life was almost always rural — and very short. Until the outbreak of World War I, global population growth was perilously contingent — the race between deaths and births, desperately close. From the dawn of our species until the 20th century, human numbers increased painfully slowly. Although uncertainty is obviously inherent in such calculations, we can nonetheless suggest that human numbers could not have grown on average by more than three one-hundredths of 1 percent per century over the 50,000 years preceding 1900. For almost all of history — and pre-history — “population balance” was enforced by recurrent and disastrous setbacks, including the regular disappearance of clans, nations, and even entire civilizations.

Then, over the course of the 20th century, the human population suddenly quadrupled — from very roughly 1.5–1.6 billion around 1900 to about 6.1 billion in 2000 (a much more solid figure, given the universality of population censuses nowadays). During the century, the tempo of world population growth accelerated by something like two orders of magnitude over the previous epochal pace, and human numbers virtually everywhere surged on an unprecedented scale.

The full text of this article was originally published by Current History .